Children could be put at risk if large nursery chains are allowed to profit at the expense of quality and safety, as has happened in the US, claims Marci Andrews, of the Center for Childcare Workforce.
American wages have been driven down, she said, leaving children in the hands of untrained teenagers. "In some states nursery workers need only be aged 18 and have a basic high-school diploma," said Ms Andrews at a London conference organised by the charity, the Daycare Trust.
CCW's research found low rates of pay despite a three-fold increase in government subsidy to the private sector. In fact, those chains receiving the biggest government grants paid their staff the worst.
The past 10 years have seen a huge increase in American government funding for childcare, with the federal government distributing a childcare development block grant to individual states.
Social reforms under the Clinton administration, such as welfare-to-work schemes similar to the ones Chancellor Gordon Brown plans here, have also directed extra funds towards childcare.
Ms Andrews said: "The lessons we've learned over the past 10 years are that millions of dollars have been infused into childcare expansion, but too few of those dollars have gone on improving wages and conditions, the two things which in turn improve choice and quality."
Colette Kelleher, director of the Daycare Trust, said she was confident the British strategy would avoid mistakes made in the States.